CARB verified that Engelhard’s DPX filters reduce soot from diesel engines some 85% when with low-sulfur diesel fuel – fuel that has a sulfur content of only 15 parts per million. The DPX filter has been approved for retrofit use only on Cummins M-11 and ISM diesel engines at the moment, though the company said it is working on approval from other engine manufactures, including Caterpillar, Mack, International and Volvo.
The U.S. Environmental Protection Agency (EPA) has also approved Engelhard’s DPX filter for the agency’s Voluntary Diesel Retrofit Program. That approval means states will be able to obtain State Implementation Plan (SIP) credits for heavy-duty diesels retrofitted with DPX filters.
EPA established the Voluntary Diesel Retrofit Program to create an incentive for states to begin cleaning up diesel pollution immediately, even though new federal emission standards for diesel engines do not take effect until 2004. Under the program, state air-quality planners can work with diesel fleet operators to choose approved emission-control technologies. States determine the amount of SIP credits to which they are entitled based on the pollution-control technologies implemented.